ng-click directive not passing desired parameter - angularjs

Question

I have the following piece of angular code: (it's a modal-popover menu which uses the following js library: http://scruffles.github.io/BootstrapModalPopover/).
<div ng-repeat="purchasedItem in purchased" class="row item_summary">
<!-- edited for brevity -->
<div id="{{purchasedItem.code}}-popover" data-product-id="{{purchasedItem.code}}" class="popover" style="display: none;">
<div class="arrow"></div>
<h3 class="popover-title" style="display: none;"></h3>
<div class="popover-content">
<div class='popover-menu-left'>
<button class="btn btn-sm btn-danger" ng-click='purchasedItems.removePurchasedItem(purchasedItem)'>Verwijderen</button><br>
</div>
<div class='popover-menu-right-template'>
<div class='number-content' style="display: none;">
<div ng-controller="numpadCtrl as numpad" class="numpad">
<!-- edited for brevity -->
<input type="button" class="btn btn-sm" value="enter" data-item-id='{{purchasedItem.code}}' ng-click="numpad.flushNumber(purchasedItem.code)"></input>
</div>
</div>
</div>
<div class='popover-menu-right-content'>
</div>
</div>
</div>
</div>
the problem lies with this particular piece of code:
<input type="button" class="btn btn-sm" value="enter" data-item-id='{{purchasedItem.code}}' ng-click="numpad.flushNumber(purchasedItem.code)"></input>
The data-item-id attribute was added just to see if I could get retrieve the code - this works just fine! But when I set a breakpoint in the flushNumber function, the parameter passed is undefined.
The code for the numpad controller is the following (it doesn't really do anything yet)
sportOaseControllers.controller('numpadCtrl', ['$scope',
function($scope) {
var parent = this;
parent.currentEntry = "";
parent.addNumber = function (number) {
parent.currentEntry = parent.currentEntry.concat(number);
console.log(parent.currentEntry);
};
parent.cancel = function() {
console.log('cancelled!');
parent.currentEntry = "";
};
parent.flushNumber = function(code) {
console.log('flushing!' + code);
}
}]);
The only thing which might be a clue is that the $scope injected into the numpad controller is null - my knowledge of angular is too minimal to do any real debugging however. Can somebody point me in the right direction?

Answer 1

This is a working JSFiddle, what AngularJS version do you have?
controller as was introduce since 1.2 it's not available before that.
HMTL:
<div ng-app ng-controller="FirstCtrl">
{{purchasedItem}}
<div ng-controller="numpadCtrl as numpad" class="numpad">
<!-- edited for brevity -->
<input type="button" class="btn btn-sm" value="enter" data-item-id='{{purchasedItem.code}}' ng-click="numpad.flushNumber(purchasedItem.code)"></input>
</div>
</div>
JS:
function FirstCtrl($scope) {
$scope.purchasedItem = {
code: 'hello'
};
}
function numpadCtrl($scope) {
this.flushNumber = function (code) {
console.log(code);
}
}